RANCHO CUCAMONGA -- Sheriff's detectives are investigating five students at Etiwanda and Rancho Cucamonga high schools suspected of distributing semi-nude images of fellow students.

The students, between the ages of 15 and 16, spread the images by text message and social media, according to the San Bernardino County Sheriff's Department.

No arrests had been made, but sending sexually explicit photos of children is a felony, department spokeswoman Jodi Miller said.

"Sending it to someone else is a crime, and somebody else forwarding those pictures is a crime," Miller said.

Students prompted the investigation, said Mat Holton, the superintendent of Chaffey Joint Union High School District.

"It was brought to our administration's attention by students coming forward saying, 'Hey, there are some inappropriate things involving our peers on the Internet, and we think you should know,'" he said.

A school security officer at Etiwanda High looked into the matter and reported the sexting incidents to the Sheriff's Department on Wednesday morning.

The officer learned a boy had four semi-nude photos of female students on his cellphone and sent them to others via text message. Deputies have identified two of the girls in the photos.

The students being investigated - the boy who initially sent the photos and four girls - attend Rancho Cucamonga and Etiwanda high schools.

"Communicating through social media is what high-school-aged kids do," Holton said. "In a high school district of over 25,000 teens, it's incumbent on us to educate them on the etiquette but more importantly the danger of sending pictures and other materials. "

The CJUHSD discusses the issue throughout the year, starting the first week of school. And this week's news will likely mean additional conversations.

"This morning, I sent a message to every teacher throughout the district, just to bring them up to speed with the information that I could share (and) just to encourage them, if they're comfortable, to use this as a teachable moment with their students," Holton said.

Etiwanda student Elijah Hunter said it is crazy how quickly something can spread on social media and that some of his peers may need to lessons on the consequences of sending explicit images.

"It should (be taught), because in the future, you're not going to be able to get a job. I think it's very important," Elijah, 16, said.

Anthony Wilson, a father whose son attends Etiwanda, said he advises his son not to post embarrassing pictures on the Internet, but believes educators must also impart these lessons to students.

"It would definitely help, because parents are definitely not supervising their kids," Wilson said waiting to pick up his son from school on Thursday.

This is San Bernardino County's second case in three years involving high school students caught sexting.

Four 15-year-old boys from Yucaipa High School were suspected of posting nude photos of at least eight teen girls on the Internet in April 2010.

"We try to make sure that kids know this and to educate them about it. But you know, being young, they think nothing will happen to them," said Yucaipa-Calimesa Joint Unified Superintendent Sherry Kendrick.

YCJUSD educators discuss the issue in health class and during counseling sessions.

"We do talk to them about making sure what they're sending is appropriate and that they can get into serious trouble," she said. "I think the girls who are sending it, those are the ones who I don't think realize they could be guilty of a serious crime as well. "

The YHS photos were voluntarily sent by the victims - 14- and 15-year-old girls - to their friends. The pictures were then circulated among a group of other students. A student accumulated the photos and posted them on at least one social networking site, according to sheriff's officials.

"You can't forward it simply because it was sent to you. You need to delete it as well," Kendrick said. "As a parent of two boys, I think about what could happen to them if they got a photo and shared it as well, not recognizing the seriousness as well. "

The Sheriff's Department has tried to address the issue by holding presentations at schools and for faith-based groups about sexting and its penalties. The department has also developed a DVD on the subject and distributed more than 100 copies to county schools.

"It's a tough thing, and it's something that the parents, school and community all have to handle together," Kendrick said.

Groups wishing to schedule a presentation with the Sheriff's Department on sexting may call 909-387-3700.